Semiconductor device

ABSTRACT

A semiconductor device with which a panel having a large area or a narrowly margined with the circumferential space minimized can be manufactured stably with a high yield. The semiconductor device comprises a TFT substrate having a plurality of pixels of a plurality of TFT (thin film transistors) provided on the substrate in which a peripheral wire is arranged along the outer periphery of the TFT substrate and connected to a constant potential.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a semiconductor device comprising a pluralityof functional elements arranged on a substrate.

2. Related Background Art

To date, thin film transistors prepared by using an amorphous siliconthin film for functional elements have a wide variety of applications asswitching devices including display devices such as liquid crystalpanels and organic EL panels as well as optical sensor panels where theyare used in combination with PIN photodiodes comprising an amorphoussilicon thin film like TFT elements or photoelectric conversion elements(to be referred to as optical sensor elements hereinafter) such as MISphotocapacitors and TFT optical sensors.

In recent years, efforts have been paid to develop medical applicationsfor optical sensor panels. Particularly, indirect-type radiation imagingapparatus adapted to transform radioactive rays into visible light bymeans of fluorescent substances to indirectly read the obtained opticalinformation by means of an optical sensor panel and direct typeradiation imaging apparatus comprising TFT devices and amorphousselenium to directly transform radioactive rays into electric signalshave been developed.

FIG. 15 shows an equivalent circuit diagram of an optical sensor panelcomprising TFT elements and PIN photodiodes and FIG. 16 shows aschematic cross sectional view of such an optical sensor panel. In FIG.15, reference numerals 1010, 1020 and 1030 respectively denote a PINoptical sensor, a TFT and a signal wire, whereas reference numerals 1040and 1050 respectively denotes a TFT drive wire and a bias wire of thePIN optical sensor.

In FIG. 16, reference numerals 2010, 2020, 2030, 2040, 2050, 2060, 2070and 2080 respectively denote a glass substrate, a gate wire, a gateinsulating film, an i-type a-Si layer, an SiN layer, an n+ ohmic contactlayer, a source/drain electrode and a sensor lower-electrode whereasreference numerals 2100, 2110, 2120 respectively denotes P-, I- andN-type a-Si layers. Reference numeral 2090 denotes a sensorupper-electrode and reference numeral 2130 denotes an SiN protectionfilm.

The incoming beam that is carrying image information is subjected tophotoelectric conversion by the PIN optical sensor 1010 and its electriccharge is stored in a sensor capacity C1. Subsequently, when the TFT1020 is turned on, the electric charge is distributed to a capacity C2formed at the crossing of the signal line 1030 and the TFT drive wire1040 so that the change in the potential of the signal line 1030 is readand output.

Currently, improvements are required of the above-described opticalsensor panels in terms of substrate size and process precision in orderto meet the demand for a larger display area and a higher degree ofdefinition. However, any such improvements may inevitably entail a hugeamount of investment in plant and equipment and a long introductorypre-operational period so that doubts may be cast on such an idea.

In view of this problem, there have been proposed semiconductor devicesadapted to produce a large display area by bonding a plurality ofrelatively small panels. Such semiconductor devices may be realized byusing existing plants and equipment for manufacturing small substrates.

FIG. 17 is a schematic perspective view of a radiation image readingapparatus having a large display area and formed by bonding four opticalsensor panels. FIG. 18 is a schematic cross sectional view of the deviceof FIG. 17. In FIG. 17, reference numerals 3010, 3020, 3050, 3060 and3400 respectively denote an optical sensor panel, a base, a fluorescentpanel, a flexible substrate and a chassis.

Referring to FIG. 18, the base 3020 is used to rigidly hold four opticalsensor panels 3010 and typically made of lead that absorbs radioactiverays and protects the electric components arranged therebelow. Thesensor panels 3010 are bonded to the base 3020 by way of a firstadhesive layer 3030, while the fluorescent panel 3050 for transformingradioactive rays into visible light is bonded to the sensor panels 3010by way of a second adhesive layer 3040. In FIG. 18, reference numeral3070 denotes a printed substrate for driving the sensor panels andreference numeral 3060 denotes a flexible substrate for connecting theprinted substrate 3070 and the sensor panels 3010.

In FIG. 18, there are also shown a cabinet 3200, a lid 3210, a cover3230 typically made of lead and adapted to protect the electriccomponents, feets 3240 for rigidly securing the printed substrate 3070and angles 3250 firmly securing the base 3020 to the cabinet 3200. Notethat the chassis 2400 comprises members denoted by 3200, 3250. A sensorunit is formed by firmly securing the radiation sensor 3300 within thechassis.

However, when bonding a plurality of panels in a manner as describedabove, the precision level of the boundaries and that of the clearancesseparating them are of vital importance.

FIG. 19 is a schematic plan view of four bonded panels. FIG. 20 is anenlarged schematic plan view of a central part of the four bonded panelsof FIG. 19, illustrating the boundaries of the panels. In FIG. 20, Pdenotes the pitch of arrangement of pixels and Pc denotes the distancebetween the centers of two pixels that belong to different panels andare arranged adjacently relative to each other. In general, correctionby way of image processing can properly be carried out, when Pc<2P orthe clearance between two panels is made to be less than the size of onepixel. In other words, each sensor panel has to be cut with a margin ofseveral tens of micrometers from the edges of the pixels.

Any attempt for meeting the above requirement is accompanied by theproblems as listed below and can end up with a poor manufacturing yieldand a poor performance unless they are solved to a satisfactory extent.

1. Some of the pixels of an optical sensor panel can be adverselyaffected by a cutting operation due to problems such as chipping and/ordisplacement. Then, the reliability of the sensor panel is lowered afterassembling. FIG. 21 is a schematic plan view of a cut area of a sensorpanel comprising a pixel 4010 and a protection film 4020 typically madeof SiN. In FIG. 21, 4030 denotes a notch formed typically by chippingand 4040 denotes an end facet produced by the cutting. As seen from FIG.21, the protection film 4020 is partly damaged by notches 4030. As aresult, although the sensor panel operates properly in the initialstages, it has been confirmed that its output fluctuates when it issubjected to high temperature and high humidity.

2. Pixels can be destructed by static electricity appearing in thecourse of assembling of the panels. Normally, insulating items such asglass substrates can become electrically charged with ease when peeledoff in a vacuum chuck stage and/or scrubbed by blown air. When the panelis just brought close to an object having an electric potentialdifference such as a grounded cabinet, an electric discharge occurs todestroy some or all of the pixels of the panel, particularly thosearranged at the corners. Then, a poor manufacturing yield can result.

3. A pixel of the assembled sensor panels can be destroyed along the cutedges, particularly at the corners, when static electricity isaccumulated to 2 to 3 kV in the course of handling the panels in theassembling process.

SUMMARY OF THE INVENTION

In view of the above identified problems, it is an object of the presentinvention to provide a semiconductor device with which a panel having alarge area or a narrowly margined panel with the circumferential spaceminimized can be manufactured stably with a high yield.

More specifically, it is a first object of the present invention toprovide a semiconductor device provided with a slice check wire fordetermining the acceptability of the operation of cutting the panels inorder to ensure that the panels to be bonded are cut and bondedaccurately, said slice check wire being located at a position with whichreliability can be secured to electrically check any possible damagessuch as chippings to the protection film and other components producedin the cutting process in order to secure the reliability of the productafter the assembling process.

A second object of the present invention is to provide a semiconductordevice in which any electric cross talks are suppressed by fixing theelectric potential of the slice check wire to a constant level.

A third object of the present invention is to provide a semiconductordevice having an anti-charge feature for securing the stability and thereliability of the device, which can be achieved by electricallyconnecting the slice check wire to the drive wires of TFTs or the biaswires of the optical sensor in order to improve the resistance againstelectrostatic discharge failures and also by fixing the electricpotential of the slice check wire to a constant level.

According to the invention, the above objects are achieved by providinga semiconductor device comprising a TFT substrate having a plurality ofpixels of a plurality of TFT (thin film transistors) provided on thesubstrate, slice lines for cutting the TFT substrate being arrangedalong the periphery of said TFT substrate, peripheral wires beingarranged between said slice lines and said TFT substrate.

Preferably, said peripheral wires are connected to at least the drivewires or the signal wires of said TFTs. Preferably, each pixel of saidTFT substrate comprises a TFT element and a photoelectric conversionelement and said peripheral wires are electrically connected to the biaswires of the photoelectric conversion element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit diagram of an equivalent circuit of afirst embodiment of the invention.

FIGS. 2A, 2B, 2C, 2D and 2E are schematic cross sectional views of thepanel section of the first embodiment of the invention including TFTsand photoelectric convesion elements, illustrating differentmanufacturing steps.

FIG. 3 is an enlarged schematic plan view of a central part of the fourbonded panels of the first embodiment, illustrating the boundaries ofthe panels.

FIG. 4 is an enlarged schematic plan view of one of the panels of thefirst embodiment, illustrating a corner thereof.

FIG. 5 is a schematic plan view of bonded panels of a second embodimentof the invention.

FIG. 6 is a schematic plan view of a single panel of the secondembodiment.

FIG. 7 is a schematic circuit diagram of an equivalent circuit of athird embodiment.

FIG. 8 is a schematic circuit diagram of another equivalent circuit ofthe third embodiment.

FIG. 9 is a schematic circuit diagram of an equivalent circuit of thethird embodiment, illustrating the electric potential of the peripheralarea of the driver for driving a TFT.

FIG. 10 is a schematic partial plan view of the third embodiment,illustrating the connection between TFT drive wires.

FIG. 11 is a schematic cross sectional view of the third embodimenttaken along line 11—11 in FIG. 10.

FIG. 12 is a schematic partial plan view of the third embodiment,illustrating the connection between a TFT drive wire.

FIG. 13 is a schematic cross sectional view of the third embodimenttaken along line 13—13 in FIG. 12.

FIG. 14 is a schematic circuit diagram of an equivalent circuit of afourth embodiment of the invention.

FIG. 15 is a schematic plan view of a known optical sensor.

FIG. 16 is a schematic cross sectional view of a known PIN opticalsensor.

FIG. 17 is a schematic perspective view of a known radiation imagereading apparatus.

FIG. 18 is a schematic cross sectional view of the known radiation imagereading apparatus of FIG. 17.

FIG. 19 is a schematic plan view of bonded panels.

FIG. 20 is an enlarged schematic plan view of a central part of thebonded panels of FIG. 19.

FIG. 21 is a schematic plan view of a cut area of a sensor panel.

FIG. 22 is a schematic illustration of a system using a semiconductordevice according to the invention for an X-ray examination apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described in greater detail byreferring to the accompanying drawings that illustrate preferredembodiment of the invention.

(First Embodiment)

The first embodiment of a semiconductor device according to theinvention will be described which comprises TFT elements and MIS opticalsensors and are applied to a radiation image reading apparatus. FIG. 1is a schematic circuit diagram of an equivalent circuit of a firstembodiment of the invention. In FIG. 1, reference numerals 11, 12 and 13respectively denote a driver for driving a TFT, a signal processingamplifier and another driver for driving an MIS optical sensor. FIG. 1also shows MIS sensors C11 through C35, TFTs T11 through T35, TFT drivewires Vg1 through Vg3, signal wires Sig1 through Sig5 and bias wires Vs1and Vs2.

The MIS optical sensors C11 through C35 are provided to receive opticalsignals to be applied to the bias wires Vs1 and Vs2 from the driver 13.The electric charges of each optical signal is stored in the MIS opticalsensor. The accumulated electric charges are then sequentially read outby the TFTs (T11 through T35) by way of the signal lines Sig1 throughSig5 and the signal processing amplifier. The TFTs are sequentiallyturned on/off by signals applied thereto by the TFT driver 11 by way ofthe TFT drive wires Vg1 through Vg3. In FIG. 1, Sc denotes a slice checkwire whose electric potential is held to the ground level by the TFTdriver and the MIS optical sensor driver.

Now, the preparing steps of the embodiment will be briefly described byreferring to FIGS. 2A through 2E, showing schematic cross sectionalviews of an optical sensor panel.

(1) As shown in FIG. 2A, a Cr film is formed on a glass substrate 101 toa thickness of 1,000 Å by sputtering and then lower electrodes 102 ofthe MIS optical sensors, gate electrodes 103 and gate wires 104 of theTFTs, slice lines for cutting the panel and slice check wire areprovided there by means of a patterning operation.

(2) Then, as shown in FIG. 2B, a silicon nitride (SiN) film 105, anamorphous silicon (Si) film 106, an ohmic (n+) layer 107 aresuccessively formed by plasma CVD to respective thicknesses of 3,000 Å,5,000 Å and 1,000 Å and then contact holes 108 for connecting the lowerelectrodes of the MIS optical sensors and the TFTS-D electrodes andthose for drawing wires are provided typically by CDE.

(3) Thereafter, as shown in FIG. 2C, an aluminum (Al) film is formed bysputtering to a thickness of 1 μm and TFTS-D electrodes 109, signallines 110 and bias wires 111 of the optical sensors are formed there byway of wet etching.

(4) Subsequently, as shown in FIG. 2D, the ohmic (n+) layer 107 at theTFT gap is removed by means of RIE to form a TFT channel 112.

(5) Then, as shown in FIG. 2E, the panel is processed for elementisolation and a silicon nitride (SiN) film 113 is formed as a protectionfilm by plasma CVD to a thickness of 9,000 Å. Thereafter, openings areformed therethrough for the pads of the drawn wires typically by RIE.

As a result of the above steps, a single panel is produced and thenchecked for any defects to determine if the panel is acceptable or not,thereby completing the early stage of the process.

Then, in the middle stage of the process, the components of the opticalsensor panel are electrically mounted.

(6) Polyimide is applied by spin coating and then cured by heat.Subsequently, the panel is cut along the slice lines to predetermineddimensions.

(7) The conductivity of the slice check wire is examined.

(8) Electric connections including TAB connections and PCB connectionsare established and subsequently the slice check wire is checked againfor electric conductivity.

With the above steps, modules to be bonded together are produced. Then,in the final stage of the process, they are assembled to produce a largepanel.

(9) The panels are bonded to the base and then a fluorescent panel isbonded thereto. Thereafter, an Al sheet is bonded.

(10) The resulting assembly is housed in a cabinet and subjected to afinal examination.

Thus, a complete semiconductor device to be used for a radiation imagereading apparatus is produced. Since the risk of damage due to staticelectricity is reduced after connecting the drivers, the slice checkwire may be cut and removed after mouting the drivers in position,although it may be left there if it does not give rise to any problem.

FIG. 3 is an enlarged schematic plan view of a central part of the fourbonded panels of the first embodiment, illustrating the boundaries ofthe panels. The pixel size of this embodiment is 160 μm. In FIG. 3, thecenter of pixel refers to the center of gravity of the optical sensor,which agrees with the optical center of the pixel. Therefore, so far asthe distance separating the centers of any two adjacently located pixelsof two adjacent panels is smaller than the size of two pixels or 320 μm,the area to be used for the bondig can be increased so that the panelscan be cut safely. This can be achieved when the centers of the opticalsensors are positioned toward the center of the bonded panels byappropriately arranging TFTS. With this embodiment, the distanceseparating the pixel regions of two adjacent panels can be increasedfrom 160 μm to 188 μm or 202 μm.

FIG. 4 is an enlarged schematic plan view of one of the panels of thefirst embodiment, illustrating a corner thereof. In FIG. 4, referencenumerals 41, 42 and 43 respectively denotes a slice line, a slice checkwire and an SiN protection film, whereas point “a” shows the center ofgravity of the pixel.

The SiN protection file 43 is separated from the edges of the pixel by25 μm and the slice check wire 42 is arranged in the SiN protection filmwith the minimal width to secure its performance in a reliability testunder high temperature/high humidity. The panel is sliced so as to cutoff the slice lines. Note that the slice liens are separated from thecorresponding respective edges of the SiN protection film by 45 μm toprovide a margin for accommodating it to any displacement of chipping orslicing. The margins are made free from the SiN protection film,because, if cracks appear in the SiN protection film, they can beextended to the pixel.

How, the slice check line of this embodiment is used will be discussedbelow. As pointed out above, if the SiN protection film is damaged byany unexpected displacement due to slicing or chipping, the slice checkline can also be damaged. However, by checking electric conductivity bymeans a pad Cp arranged on the slice check wire shown in FIG. 1, anyabnormal condition of the panel is detected so that any defective sensorpanels can be prevented from being mingled with good ones.

As a result, it is now possible to by far reliably detect defectivedevices if compared with conventional visual examination processes.Additionally, it is also possible to examine each device by means of theslice check wire at significant points in the subsequent steps so thatabsolutely no defective devices may be detected after bonding aplurality of optical sensor panels for each device.

Particularly, since pixel destructions due to static electricity canoccur anytime until the TFT driver and the photoelectric conversionelement driver are mounted and become electrically operable, theexamination using the slice check wire may have to be repeated untilthat time.

While the above embodiment is described in terms of TFTs used asfunctional elements, the present invention is by no means limitedthereto and the TFTs may be replaced by diodes or thin film diodes.

(Second Embodiment)

While the circuits for driving the elements of the first embodiment arearranged only on are side of the substrate, this embodiment is providedwith drive circuits arranged on both sides of the panel in order toperform a high speed drive operation. In this embodiment, a pair ofsensor panels are bonded together. FIG. 5 is a schematic plan view ofthe panel section of a second embodiment of the invention, illustratinghow panels are bonded. In FIG. 5, reference numerals 101, 102 denotesrespective sensor panels and reference numeral 103 denotes an amplifierside leading wire connected to an amplifier IC, whereas referencenumeral 104 denotes a driver side leading wire connected to a driver IC.For each of the sensor panels of this embodiment, a driver side leadingwire is arranged on each side of the panel to realize a high speed driveoperation.

As in the case of the first embodiment, after a slice check wire isarranged along the periphery of the TFT substrate and cut at the slicelines, it is possible to check the electric conductivity to detect anydefective device. If a single sensor panel has dimensions sufficientlylarge for forming a semiconductor device, no bonding operation isrequired and hence the drivers may be arranged on both sides of thepanel. If it is desirable to locate the pixel region extremely near thechassis, a single sensor panel is used in which the cutting section isarranged in the direction that is required. Then, pixels may be read inareas close to the chassis. FIG. 6 is a schematic plan view of the panelsection of the second embodiment realized by using a single panel. InFIG. 6, there are shown a signal reading circuit 105, a sensor drivecircuit 106 and a chassis 107. As seen from FIG. 6, it is possible toarrange a peripheral pixel area A close to the chassis and to read theimage in the region close to the chassis.

While the above embodiment is described in terms of TFTs used asfunctional elements, the present invention is by no means limitedthereto and the TFTs may be replaced by diodes or thin film diodes.

(Third Embodiment)

The third embodiment of semiconductor device is applied to a radiationimage reading apparatus and comprises TFT elements and MIS photoelectricconversion elements. FIG. 7 is a schematic circuit diagram of anequivalent circuit of the second embodiment. In FIG. 7, referencenumeral 11 denotes a TFT driver and reference numeral 12 denotes asignal processing amplifier, whereas reference numeral 13 denotes an MISphotoelectric conversion element driver.

In this embodiment, wires Vs1, Vs2, which are bias wires of opticalsensors, are connected to each other by way of resistance Rvs.Additionally, TFT drive wires Vg1 through Vg3 are connected to eachother by way of resistance Rs, while wires Vs1 and Vg1 are connected toeach other by way of resistance Rv. Slice check wire Sc is connected towire Vs4 by way of resistance Rvc and to wire Vg1 by way of resistanceRgc. Alternatively, it may be connected to the signal lines or only tothe TFT drive wires as shown in FIG. 8. While not shown, it is alsopossible to connect it only to the bias wires.

If the resistance between the TFT driver and the first TFT is set to Roand the resistance between the Vg wires is set to Rs, a resistance withwhich the ON voltage Vgh applied to the Vg wires does not affect anyadjacent lines may be selected for the resistance Rs. Note that theadjacent lines are held to the OFF voltage Vg1.

FIG. 9 is a schematic circuit diagram of an equivalent circuit of thesecond embodiment, illustrating the electric potential of the peripheralarea of the driver for driving a TFT. Referring to FIG. 9, the adjacentlines can be held OFF if the potential Va of point “a” is lower than thethreshold voltage Vth of the TFTS.

Vth>Va=Vg 1+(Vgh−Vg 1)×Ro/(Rs+2Ro)(1) Rs>Ro(Vg 1−Vth−2Vth)/(Vth−Vg 1)

Since Vg1=−5V, Vgh=15V, Vth=2V and Ro=100 Ω; then Rs>86 Ω.

Similarly, as for the resistance Rv, since Vsh=9V at the time when thebias wires Vs of the optical sensors are used to read light, Vsh−Vg1=15Vin conparison with Vgh−Vg1=20V above. Thus, any failure of the TFTs canbe prevented by driving the Vs wires if at least Rv>Rs. If fluctuationsof the Vs potential are to be held within the range in which no problemis caused with respect to the performance, they have to be less than 1%.Then, the resistance Rv needs to satisfy Rv>100×Ro. In this embodiment,it is satisfied if Rv>10 kΩ. As for Rvs, in order that fluctuations ofthe bias voltage of the optical sensors are less than 1%, Rvs need tostatify Rvs>100×Ro.

Furthermore, if Vg1=0V in formula (1) above, the connection resistanceRgc between the Sc wire, or the slice check wire, and the Vg1 wire isequal to 550 Ω, or Rgc=550 Ω. Fluctuations of the bias voltage of theoptical sensors can be held less than 1% if the connection resistanceRvs between the Sc wire and the Vs4 wire is greater than 100×Ro, orRvs>100×Ro.

In this embodiment, any related wires can be connected by way of anohmic (n+) layer. A standard value of 1MΩ is selected to provide eachresistance with an enough margin.

FIG. 10 is a schematic partial plan view of the third embodiment,illustrating how Vg wires are connected. In FIG. 10, reference numerals51 and 52 respectively denote an Al wire and a Cr wire, whereasreference numerals 53 and 54 respectively denote a contact hole and ann+ connecting wire.

When connecting the Vg wires by way of an n+ layer, the Al wires areconnected to the respective Cr wires by way of respective contact holesin order to reduce the wire resistance of the Vg wires in the areasother than the pixel region. The Al wires are connected by way of an n+layer.

FIG. 11 is a schematic cross sectional view of the third embodimenttaken along line 11—11 in FIG. 10. In FIG. 11, reference numerals 58 and55 respectively denotes a glass substrate and a gate insulating film andreference numerals 56 and 57 respectively denotes a semiconductor layerand an n+ ohmic contact layer. In this embodiment, the n+ layer is madeto have a thickness of 1,000 Å as in the case of Embodiment 1 and has asheet resistance of 100 kΩ/□. Since the pitch of pixel arrangement is160 μm, the value of 1MΩ can be achieved by using ten or more than tensheets. In this embodiment, any wires are connected with a clearance of10 μm. Similarly, the Vs wires are connected by way of an n+ layer.

Now, the technique of connecting a Vg wire and a slice check wire willbe described below. FIG. 12 is a schematic partial plan view of thethird embodiment, illustrating how a TFT drive wire and a slice checkwire are connected. The slice check wire that is a Cr wire is connectedto the Vg wire by way of a contact hole. FIG. 13 is a schematic crosssectional view of the third embodiment taken along line 13—13 in FIG.12. The Vg wire 51 and the slice check line 52 are connected by way ofcontact hole 53. Here again, the n+ layer is so drawn as to make thewire resistance equal to 1MΩ. The slice check wire may be cut andremoved in the area connecting the TFT drive wires and the photoelectricconversion element drive wires after checking the conductivity of theslice check line or simply left there if it does not interfere with theoperation of the related elements by appropriately adjusting theconnection area.

While the above embodiment is described in terms of TFTs used asfunctional elements, the present invention is by no means limitedthereto and the TFTs may be replaced by diodes or thin film diodes.

(Fourth Embodiment)

Now the fourth embodiment of the invention will be described. In thisembodiment, the slice check line and the Vs wires are connected withoutspecifically providing any resistance. FIG. 14 is a schematic circuitdiagram of an equivalent circuit of a fourth embodiment of theinvention. In this embodiment, the Vs4 wire and the slice check wire Scare connected in the same layer, although they may be alternativelyarranged in different layers and connected between the different layers.Still alternatively, the Vs1 or Vs2 wire may be connected to the Scwire. In this embodiment, the electric conductivity of the slice checkwire is checked with a pad Cp for conductivity check to check defectivesafter cutting the panels, so that the slice check wire may be firmlyheld to a constant potential, which is not the ground potential, andhence the elements of the device can be protected against damages due tostatic electricity.

The present invention is also effective for narrowing the margins ofliquid crystal panels. A liquid crystal panel is prepared by arranging apair of glass substrates, forming elements on the substrates, cuttingthe substrates to desired dimensions, subsequently bonding thesubstrates and pouring liquid crystal in the space between thesubstrates. Then, electric components including drivers are mountedtherein. Therefore, in the case of a liquid crystal again, defectiveproducts can be prevented from being mingled with good ones byconnecting the slice check wire to the drive wires and examining theelectric conductivity of the slice check wire. Additionally, the pixelscan be protected against demages due to static electricity by connectingthe TFT control lines to the slice check wire. Since normally a pair ofsubstrates are bonded together and liquid crystal is poured into thegaps separating the substrates in the process of manufacturing liquidcrystal panels, the conductivity check may be conducted either before orafter bonding the substrates. For a liquid crystal panel, it is notnecessary to keep the potential of the slice check wire constantly tothe same level.

While the above embodiment is described in terms of TFTs used asfunctional elements, the present invention is by no means limitedthereto and the TFTs may be replaced by diodes or thin film diodes.

(Fifth Embodiment)

FIG. 22 is a schematic illustration of a system using a semiconductordevice according to the invention for an X-ray examination apparatus.

Referring to FIG. 22, X-rays 6060 generated by an X-ray tube 6050 aremade to be transmitted through the chest 6062 of a patient or subject6061, and enter the photoelectric converter 6040 provided on the surfacewith a fluorescent substance. For apparatus in which a substance (e.g.GaAs) having sensibility to radioactive rays such as X-ray is employed,however, the apparatus can sense radioactive rays and can be used as aradiation detection apparatus without providing a wavelength convertersuch as a fluorescent substance. The incoming X-rays contain informationof the interior of the patient 6061. The fluorescent substance emitslight as a function of the incoming X-rays and the photoelectricconverter 6040 converts the emitted light into electric information,which is digitized and processed by an image processor 6070 so that itcan be observed on a display 6080 in the control room.

The obtained information can be transferred to a remote site by way ofan appropriate transmission means such as a telephone wire 6090 so thatit may be displayed on a display 6081 in a doctor room of the remotesite or stored in a storage means such as an optical disk. Therefore,the doctor at the remote site can diagnose the patient. The informationmay also be recorded on a film 6110 by means of a film processor 6100.

What is claimed is:
 1. A photoelectric converter device having aplurality of pixels formed on a substrate, comprising: a slice checkwire for checking acceptability of a cut edge of said substrate, saidslice check wire being arranged outside a region where said pixels arearranged and being disposed on a first wire layer among a plurality ofwire layers, closest to said substrate, on said substrate.
 2. Thephotoelectric converter device according to claim 1, wherein said wireis connected to a constant electric potential.
 3. The photoelectricconverter device according to claim 2, wherein said constant electricpotential is the ground potential.
 4. The photoelectric converter deviceaccording to claim 1, wherein said wire has a pad section for checkingelectric conductivity.
 5. The photoelectric converter device accordingto claim 1, wherein said substrate is an insulator.
 6. The photoelectricconverter device according to claim 1, wherein said pixels carry awavelength converter thereon.
 7. The photoelectric converter deviceaccording to claim 6, wherein said wavelength converter is a fluorescentsubstance.